How to Choose Vascular Access
The fastest route into the circulation in a stable casualty is a peripheral IV. But in shock, the veins that make an IV easy are the first to collapse — which is why intraosseous (IO) access has become the fallback when peripheral attempts fail. IO drives a needle into the marrow space, a non-collapsible vascular network that accepts fluids and drugs at flow rates approaching an IV.
IV vs. IO
| Route | When | Common sites |
|---|---|---|
| Peripheral IV | First choice in a casualty with accessible veins | Forearm, antecubital, hand |
| Intraosseous (IO) | When IV attempts fail or the patient is in collapse | Proximal humerus, proximal tibia, sternum |
What access is for
Access is a means, not an end. In hemorrhagic shock, doctrine favors permissive hypotension — resuscitating to a palpable radial pulse and clear mentation rather than a normal blood pressure, so a forming clot isn't blown off by aggressive fluid. Whole blood is the preferred resuscitation fluid where available. Access also delivers TXA, an antifibrinolytic most effective when given early after major hemorrhage. Stock catheters, IO drivers, administration sets, and a means to run fluids under pressure.
Building an ALS loadout? Carry both IV and IO so loss of peripheral access doesn't stop resuscitation. Anchor the kit with the trauma-response brief.
Frequently Asked Questions
When do you use IO instead of IV?
Use intraosseous access when peripheral IV attempts fail or the casualty is in shock with collapsed veins. IO reaches the non-collapsible marrow space and delivers fluids and drugs at rates approaching an IV.
Where are intraosseous sites placed?
Common IO sites are the proximal humerus (often preferred for flow and comfort), the proximal tibia, and the sternum. Site choice depends on the device, the casualty, and provider training.
What is permissive hypotension?
It is resuscitating a bleeding casualty to a palpable radial pulse and clear mental status rather than a normal blood pressure. Over-aggressive fluid can raise pressure enough to dislodge a forming clot and worsen bleeding.
Why give TXA through IV or IO access?
TXA is an antifibrinolytic that helps stabilize clots and is most effective when given early after major hemorrhage. Vascular access is how it and other resuscitation fluids are delivered in the field.
What do I need to start IV or IO access?
A working setup includes catheters or an IO driver and needles, administration (IV) sets, fluids, securement, and often a pressure infuser to drive flow. Match the loadout to your scope and protocol.
Related collections
MED-TAC International Corp. is a clinician-founded, veteran-led tactical medicine provider. Product references to CoTCCC reflect committee recommendations and do not imply FDA approval or certification. This content is educational and is not a substitute for hands-on training or medical direction.